I like this a lot, it feels like you cant hardly queeze it any more for the given size. I think you should draw more stuff like this. I'd like to see tiles relating to this piece, and a how would look the protagonist. Heck, it deserves its own game!

Thanks a ton for your critique, buddy! In hindsight it would have been better to widen the eyes by 1 pixel and border them with grey.

For the shield I tried to give some kind of hue change to create the illusion of moving it back and forth during walking. I've got absolutely no idea how to do that better on a 16x16 sprite without giving the viewer seizures, haha.

Only nitpicks I can think of are that I'm not sure if the red eyes have enough contrast towards the head and would focus more on light/dark contrast in that place, too. At least it doesn't work that well on my monitor but that doesn't mean much since I've a very cheap uncallibrated one
and the flicker on that shield while walking might be a bit too flickery, on the other hand inducing seizures sure seems like a move a possessed knight would do

Also an interesting choice for that highlight pixel! (and I imagine him or her to have chipmunk laughter)

And that foreshortening effect you used on the sword , you're quite a crafty one